the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Wind work at the air-sea interface: A Modeling Study in Anticipation of Future Space Missions
Abstract. Wind work at the air-sea interface is the transfer of kinetic energy between the ocean and the atmosphere and, as such, is an important part of the atmosphere-ocean coupled system. Since wind work involves winds and ocean currents that span a broad range of spatial and temporal scales, a comprehensive study would require access to observations of a wide range of space and time scales. In the absence of appropriate global observations, our study makes use of a new, global, coupled ocean-atmosphere simulation with horizontal grid spacing of 2–5 km for the ocean and 7 km for the atmosphere. Here we develop a methodology, both in physical and spectral space, to diagnose different components of wind work in terms of forcing distinct classes of oceanic motions, including mean currents, time-dependent large-scale currents and mesoscale eddies, and internal gravity waves such as near-inertial waves. The total simulated wind work has a magnitude of 5.21 TW, a value much larger than reported by previous modeling studies. The total wind work is first decomposed into time-mean and time-dependent components, with the former accounting for 2.23 TW (43 %) and the latter 2.98 TW (57 %). The time-dependent wind work is then decomposed into two components, a high-frequency component that forces internal gravity waves and a low-frequency component that forces mesoscale eddies and large-scale currents. The high-frequency component is positive at scales between 10 km and 1000 km and represents 75 % of the total time-dependent component. The low-frequency component is found to be positive for spatial scales larger than 275 km and ten times larger than the negative part associated with smaller spatial scales. The negative wind work acts as a surface drag that slows down surface currents and damps mesoscale eddies whereas the positive low-frequency part accelerates large-scale currents. The complex and consequential interplay of surface winds and currents in the numerical simulation motivates the need for a winds-and-currents satellite mission to directly observe these wind work components.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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- BibTeX
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- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-294', Anonymous Referee #1, 15 Jun 2022
The manuscript addresses an interesting topic, estimating global wind work and presents interesting results. I like the idea to separate the time-dependent wind work to the low and high-frequency components. Though it is well written, I recommend a major revision based on my comments below:
- A more than 5 TW global wind work has been reported before as in Yu et al. 2018 (https://doi.org/10.1016/j.ocemod.2018.07.009 ) and Yu et al. 2019 (https://doi.org/10.1016/j.ocemod.2019.05.003 ). Though they focused on the wind work over ageostrophic currents (Yu et al., 2018) and used it to explain the global EKE reduction after including ocean surface currents in the wind stress formulation. But these were not cited in this manuscript. And I encourage the authors to do a more thorough search of the topic just in case.
- I like the idea of low/high frequency wind work components but wondering if the 3.5-month data long enough. Is 3.5 month a good representation of the mean component? Is it long enough for low-frequency (seasonality)? I’d encourage the authors to extend the calculation to the whole 14-month available. This is the main reason why I recommend a major revision.
- Really minor: Line 92, “January 20 using 2012 ocean initial conditions”. I think 2012 is a typo otherwise would need to explain why 2012 not 2020.
Citation: https://doi.org/10.5194/egusphere-2022-294-RC1 -
AC3: 'Reply on RC1', Hector Torres, 27 Jul 2022
Dear reviewer,
We thank you very much for your constructive comments and suggestions, which we have taken into account in the revised version of the manuscript, as summarized below.
The manuscript addresses an interesting topic, estimating global wind work and presents interesting results. I like the idea to separate the time-dependent wind work to the low and high-frequency components. Though it is well written, I recommend a major revision based on my comments below:
- A more than 5 TW global wind work has been reported before as in Yu et al. 2018 (https://doi.org/10.1016/j.ocemod.2018.07.009 ) and Yu et al. 2019 (https://doi.org/10.1016/j.ocemod.2019.05.003 ). Though they focused on the wind work over ageostrophic currents (Yu et al., 2018) and used it to explain the global EKE reduction after including ocean surface currents in the wind stress formulation. But these were not cited in this manuscript. And I encourage the authors to do a more thorough search of the topic just in case.
Thank you for suggestion. We now cite and discuss results from following papers: Yu et al. 2018 and 2019, and Gaube et al. 2015.
- I like the idea of low/high frequency wind work components but wondering if the 3.5-month data long enough. Is 3.5 month a good representation of the mean component? Is it long enough for low-frequency (seasonality)? I’d encourage the authors to extend the calculation to the whole 14-month available. This is the main reason why I recommend a major revision.
When we started this paper, only 3 months of model output were available. In revised manuscript we have extended analysis to the last 12 months of the simulation, skipping the first two months because of spin-up issues.
- Really minor: Line 92, “January 20 using 2012 ocean initial conditions”. I think 2012 is a typo otherwise would need to explain why 2012 not 2020.
Thank you, we have corrected the typo.
Citation: https://doi.org/10.5194/egusphere-2022-294-AC3
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CEC1: 'Comment on egusphere-2022-294', Juan Antonio Añel, 16 Jun 2022
Dear authors,
After checking your manuscript, it has come to our attention that it does not comply with our "Code and Data Policy".
https://www.geoscientific-model-development.net/policies/code_and_data_policy.htmlWe can not accept a manuscript for publication that does not provide the code and the models used for the work described. Also, we request that all the configuration and input files necessary to reproduce your work are stored in one of the suitable repositories listed in our policy, and you must include the DOI. In this way, the servers that you indicate in the Data Availability statement do not comply with policies to assure long-term data archivally. Moreover, it presents a lack of detail on how to access the specific files, simply pointing to generic web pages or portals. Â Also, the statement "All rights reserved" is totally unacceptable.
Therefore, we request you that fix this issue immediately. I would not expect that it would take longer than five working days to do it. Otherwise, we will have to reject your paper for publication in Geosci. Model Dev. for not complying with the policy of the journal.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive EditorCitation: https://doi.org/10.5194/egusphere-2022-294-CEC1 -
AC1: 'Reply on CEC1', Hector Torres, 23 Jun 2022
Dear Juan Antonio Añel
We appreciate the comment, we have updated the manuscript accordingly to GMD policies. Â The channels of data distribution have been added to Data Availability section. On the other hand, codes and scripts can be downloaded from Zenodo, its DOI is included in the Code Availability section.
A copy of the updated version of the manuscript was sent to the Editorial board of Copernicus.
Â
Kind regards,
Hector Torres
JPL, Caltech
Pasadena CA, USA
Citation: https://doi.org/10.5194/egusphere-2022-294-AC1 -
CEC2: 'Reply on AC1', Juan Antonio Añel, 27 Jun 2022
Dear Dr Torres,
Unfortunately, we do not update the files during a stage in the review process. In this way, the fact that you have sent the journal a new version of the paper with the modified sections does not make this information available to the reviewers and any other person who could want to check your work.
Therefore, you must publish the new information in the Discussions forum, for example, in reply to this comment. This way, the repositories, code and data will be available to anyone, as they must be, following our editorial rules.
Please, do it as soon as possible.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2022-294-CEC2 -
CEC3: 'Reply on CEC2', Juan Antonio Añel, 27 Jun 2022
Dear Dr Torres,
My apologies for the previous comment; you can obviate it. I had not seen your reply in an independent comment with the requested information.
The code and data availability is ok now.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2022-294-CEC3
-
CEC3: 'Reply on CEC2', Juan Antonio Añel, 27 Jun 2022
-
CEC2: 'Reply on AC1', Juan Antonio Añel, 27 Jun 2022
-
AC1: 'Reply on CEC1', Hector Torres, 23 Jun 2022
-
RC2: 'Comment on egusphere-2022-294', Anonymous Referee #2, 17 Jun 2022
This study extends the work of Rai et al. (2021) to examine the importance of additional scales of variability in the context of wind work. It nicely shows the importance of high frequency variability. However, it seems to leave several aspects of this problem untouched, and these aspects substantially change the numerical results.Â
The selected drag coefficient is a reasonable choice for neutral boundary-layer stability, however, it is likely that locations with strong currents will also have substantially non-neutral boundary-layers.  While I concede that considering stability won’t qualitatively change the results, it might change the numbers by 10%, with greater impact on the high frequency numbers. The use of this assumption seems to be needless presuming that the model stress was saved, which seems like a certainty as the stresses curls are shown in the Strobach et al. 2022 paper.Â
Studies by Rhys Parfitt and colleagues suggest that the mesoscale atmosphere couples with the ocean on the same spatial scales. Does the ability to represent ocean gradients in the stress calculation (and hence ocean forcing) on spatial scales of roughly twice as fine as the atmospheric gradients cause any problems? Â This would be a concerning choice of resolutions if the atmospheric boundary-layer responds substantially to the ocean, and hence would oddly impact the feedback on ocean forcing. The authors suggest that this concern might not be a serious problem because the stress in Fig. 1 does not seem to be responding to the currents. Â This interpretation may be an artifact of the color bar, but in this form the image suggests that the atmosphere is not responding to changes in the current, suggesting that the stress described in this paper is experienced by the ocean but not be the atmosphere, consistent with the seemingly strange use of a calculated neutral stress. Guabe et al. (2015) shows that the impacts of current gradients curl are greater than the impacts of stability, further supporting the concern that winds and currents are not coupled in this study.Â
Neither this paper not the cited papers explain what information is exchanged between the ocean and atmospheric model, nor is it clear that the stress mentioned in this paper was experienced by the atmosphere, which might explain why the modeled stress values were not used in this study. In other words, it appears the atmospheric response to changes in the ocean is due only to thermodynamic changes in the ocean, as was typical with much of the early work on this subject. This raises the question of the importance of the missing atmospheric response and how those atmospheric changes would impact the ocean forcing. It would be fascinating to see this analysis carried out with a two-way coupled model that includes physics correctly coupling winds to currents, and hence changes to wind work. An evaluation of how atmospheric resolution impacts wind work would also be interesting, but is also clearly too much to ask. While this work demonstrates the importance of a high-resolution ocean on wind work and that it is important to consider surface relative winds in the calculation of wind work, it seems to largely neglect the importance of the atmosphere in the coupled ocean-atmosphere system, for which related changes in wind speed and direction could substantially impact wind work.Â
Technical corrections:Â
1) Â Â Better explain how the models are coupled by detailing the variables that are exchanged.
2) Â Â Be clear about why a neutral drag coefficient is used when model stress are available.References:
Gaube, P., D. B. Chelton, R. M. Samelson, M. G. Schlax, and L. W. O’Neill, 2015: Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping. J. Phys. Oceanogr., 45, 104–132, https://doi.org/10.1175/JPO-D-14-0032.1.
Strobach, E., Klein, P., Molod, A., Fahad, A. A., Trayanov, A., Menemenlis, D., and Torres, H.: Local Air-Sea Interactions at Ocean Mesoscale and Submesoscale in a Western Boundary Current, Geophysical Research Letters, 49, 1–10, https://doi.org/10.1029/2021GL097003, 2022.Citation: https://doi.org/10.5194/egusphere-2022-294-RC2 -
AC2: 'Comment on egusphere-2022-294', Hector Torres, 24 Jun 2022
Dear Juan Antonio Añel,
In the updated version of the manuscript, we have added the following lines:
Â
Code availability:
The exact version of the model used to produce the results used in this paper is archived on Zenodo (https://doi.org/10.5281/zenodo.6686083), as are input data and scripts to run the model and produce the plots.
Â
Data availability:
Outputs of the coupled ocean-atmosphere simulation can be found at:https://portal.nccs.nasa.gov/datashare/G5NR/DYAMONDv2/GEOS_6km_Atmosphere-MITgcm_4km_Ocean-Coupled/GEOSgcm_output/.
In particular, the dataset contained in the folder geosgcm_surf/ were used in this study.
The ocean-only LLC2160 simulation can be download fromhttps://data.nas.nasa.gov/ecco/data.php?dir=/eccodata/llc_2160/compressed. The variables used in this study are U (east-west velocity component), V (north-south velocity component), oceTAUX (east-west wind stress component), and oceTAUY (north-south wind stress component).
Â
Please, let us know if you have any more concern.
Kind regards,
Hector Torres
JPL, Caltech
Citation: https://doi.org/10.5194/egusphere-2022-294-AC2
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-294', Anonymous Referee #1, 15 Jun 2022
The manuscript addresses an interesting topic, estimating global wind work and presents interesting results. I like the idea to separate the time-dependent wind work to the low and high-frequency components. Though it is well written, I recommend a major revision based on my comments below:
- A more than 5 TW global wind work has been reported before as in Yu et al. 2018 (https://doi.org/10.1016/j.ocemod.2018.07.009 ) and Yu et al. 2019 (https://doi.org/10.1016/j.ocemod.2019.05.003 ). Though they focused on the wind work over ageostrophic currents (Yu et al., 2018) and used it to explain the global EKE reduction after including ocean surface currents in the wind stress formulation. But these were not cited in this manuscript. And I encourage the authors to do a more thorough search of the topic just in case.
- I like the idea of low/high frequency wind work components but wondering if the 3.5-month data long enough. Is 3.5 month a good representation of the mean component? Is it long enough for low-frequency (seasonality)? I’d encourage the authors to extend the calculation to the whole 14-month available. This is the main reason why I recommend a major revision.
- Really minor: Line 92, “January 20 using 2012 ocean initial conditions”. I think 2012 is a typo otherwise would need to explain why 2012 not 2020.
Citation: https://doi.org/10.5194/egusphere-2022-294-RC1 -
AC3: 'Reply on RC1', Hector Torres, 27 Jul 2022
Dear reviewer,
We thank you very much for your constructive comments and suggestions, which we have taken into account in the revised version of the manuscript, as summarized below.
The manuscript addresses an interesting topic, estimating global wind work and presents interesting results. I like the idea to separate the time-dependent wind work to the low and high-frequency components. Though it is well written, I recommend a major revision based on my comments below:
- A more than 5 TW global wind work has been reported before as in Yu et al. 2018 (https://doi.org/10.1016/j.ocemod.2018.07.009 ) and Yu et al. 2019 (https://doi.org/10.1016/j.ocemod.2019.05.003 ). Though they focused on the wind work over ageostrophic currents (Yu et al., 2018) and used it to explain the global EKE reduction after including ocean surface currents in the wind stress formulation. But these were not cited in this manuscript. And I encourage the authors to do a more thorough search of the topic just in case.
Thank you for suggestion. We now cite and discuss results from following papers: Yu et al. 2018 and 2019, and Gaube et al. 2015.
- I like the idea of low/high frequency wind work components but wondering if the 3.5-month data long enough. Is 3.5 month a good representation of the mean component? Is it long enough for low-frequency (seasonality)? I’d encourage the authors to extend the calculation to the whole 14-month available. This is the main reason why I recommend a major revision.
When we started this paper, only 3 months of model output were available. In revised manuscript we have extended analysis to the last 12 months of the simulation, skipping the first two months because of spin-up issues.
- Really minor: Line 92, “January 20 using 2012 ocean initial conditions”. I think 2012 is a typo otherwise would need to explain why 2012 not 2020.
Thank you, we have corrected the typo.
Citation: https://doi.org/10.5194/egusphere-2022-294-AC3
-
CEC1: 'Comment on egusphere-2022-294', Juan Antonio Añel, 16 Jun 2022
Dear authors,
After checking your manuscript, it has come to our attention that it does not comply with our "Code and Data Policy".
https://www.geoscientific-model-development.net/policies/code_and_data_policy.htmlWe can not accept a manuscript for publication that does not provide the code and the models used for the work described. Also, we request that all the configuration and input files necessary to reproduce your work are stored in one of the suitable repositories listed in our policy, and you must include the DOI. In this way, the servers that you indicate in the Data Availability statement do not comply with policies to assure long-term data archivally. Moreover, it presents a lack of detail on how to access the specific files, simply pointing to generic web pages or portals. Â Also, the statement "All rights reserved" is totally unacceptable.
Therefore, we request you that fix this issue immediately. I would not expect that it would take longer than five working days to do it. Otherwise, we will have to reject your paper for publication in Geosci. Model Dev. for not complying with the policy of the journal.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive EditorCitation: https://doi.org/10.5194/egusphere-2022-294-CEC1 -
AC1: 'Reply on CEC1', Hector Torres, 23 Jun 2022
Dear Juan Antonio Añel
We appreciate the comment, we have updated the manuscript accordingly to GMD policies. Â The channels of data distribution have been added to Data Availability section. On the other hand, codes and scripts can be downloaded from Zenodo, its DOI is included in the Code Availability section.
A copy of the updated version of the manuscript was sent to the Editorial board of Copernicus.
Â
Kind regards,
Hector Torres
JPL, Caltech
Pasadena CA, USA
Citation: https://doi.org/10.5194/egusphere-2022-294-AC1 -
CEC2: 'Reply on AC1', Juan Antonio Añel, 27 Jun 2022
Dear Dr Torres,
Unfortunately, we do not update the files during a stage in the review process. In this way, the fact that you have sent the journal a new version of the paper with the modified sections does not make this information available to the reviewers and any other person who could want to check your work.
Therefore, you must publish the new information in the Discussions forum, for example, in reply to this comment. This way, the repositories, code and data will be available to anyone, as they must be, following our editorial rules.
Please, do it as soon as possible.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2022-294-CEC2 -
CEC3: 'Reply on CEC2', Juan Antonio Añel, 27 Jun 2022
Dear Dr Torres,
My apologies for the previous comment; you can obviate it. I had not seen your reply in an independent comment with the requested information.
The code and data availability is ok now.
Best regards,
Juan A. Añel
Geosci. Model Dev. Executive Editor
Citation: https://doi.org/10.5194/egusphere-2022-294-CEC3
-
CEC3: 'Reply on CEC2', Juan Antonio Añel, 27 Jun 2022
-
CEC2: 'Reply on AC1', Juan Antonio Añel, 27 Jun 2022
-
AC1: 'Reply on CEC1', Hector Torres, 23 Jun 2022
-
RC2: 'Comment on egusphere-2022-294', Anonymous Referee #2, 17 Jun 2022
This study extends the work of Rai et al. (2021) to examine the importance of additional scales of variability in the context of wind work. It nicely shows the importance of high frequency variability. However, it seems to leave several aspects of this problem untouched, and these aspects substantially change the numerical results.Â
The selected drag coefficient is a reasonable choice for neutral boundary-layer stability, however, it is likely that locations with strong currents will also have substantially non-neutral boundary-layers.  While I concede that considering stability won’t qualitatively change the results, it might change the numbers by 10%, with greater impact on the high frequency numbers. The use of this assumption seems to be needless presuming that the model stress was saved, which seems like a certainty as the stresses curls are shown in the Strobach et al. 2022 paper.Â
Studies by Rhys Parfitt and colleagues suggest that the mesoscale atmosphere couples with the ocean on the same spatial scales. Does the ability to represent ocean gradients in the stress calculation (and hence ocean forcing) on spatial scales of roughly twice as fine as the atmospheric gradients cause any problems? Â This would be a concerning choice of resolutions if the atmospheric boundary-layer responds substantially to the ocean, and hence would oddly impact the feedback on ocean forcing. The authors suggest that this concern might not be a serious problem because the stress in Fig. 1 does not seem to be responding to the currents. Â This interpretation may be an artifact of the color bar, but in this form the image suggests that the atmosphere is not responding to changes in the current, suggesting that the stress described in this paper is experienced by the ocean but not be the atmosphere, consistent with the seemingly strange use of a calculated neutral stress. Guabe et al. (2015) shows that the impacts of current gradients curl are greater than the impacts of stability, further supporting the concern that winds and currents are not coupled in this study.Â
Neither this paper not the cited papers explain what information is exchanged between the ocean and atmospheric model, nor is it clear that the stress mentioned in this paper was experienced by the atmosphere, which might explain why the modeled stress values were not used in this study. In other words, it appears the atmospheric response to changes in the ocean is due only to thermodynamic changes in the ocean, as was typical with much of the early work on this subject. This raises the question of the importance of the missing atmospheric response and how those atmospheric changes would impact the ocean forcing. It would be fascinating to see this analysis carried out with a two-way coupled model that includes physics correctly coupling winds to currents, and hence changes to wind work. An evaluation of how atmospheric resolution impacts wind work would also be interesting, but is also clearly too much to ask. While this work demonstrates the importance of a high-resolution ocean on wind work and that it is important to consider surface relative winds in the calculation of wind work, it seems to largely neglect the importance of the atmosphere in the coupled ocean-atmosphere system, for which related changes in wind speed and direction could substantially impact wind work.Â
Technical corrections:Â
1) Â Â Better explain how the models are coupled by detailing the variables that are exchanged.
2) Â Â Be clear about why a neutral drag coefficient is used when model stress are available.References:
Gaube, P., D. B. Chelton, R. M. Samelson, M. G. Schlax, and L. W. O’Neill, 2015: Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping. J. Phys. Oceanogr., 45, 104–132, https://doi.org/10.1175/JPO-D-14-0032.1.
Strobach, E., Klein, P., Molod, A., Fahad, A. A., Trayanov, A., Menemenlis, D., and Torres, H.: Local Air-Sea Interactions at Ocean Mesoscale and Submesoscale in a Western Boundary Current, Geophysical Research Letters, 49, 1–10, https://doi.org/10.1029/2021GL097003, 2022.Citation: https://doi.org/10.5194/egusphere-2022-294-RC2 -
AC2: 'Comment on egusphere-2022-294', Hector Torres, 24 Jun 2022
Dear Juan Antonio Añel,
In the updated version of the manuscript, we have added the following lines:
Â
Code availability:
The exact version of the model used to produce the results used in this paper is archived on Zenodo (https://doi.org/10.5281/zenodo.6686083), as are input data and scripts to run the model and produce the plots.
Â
Data availability:
Outputs of the coupled ocean-atmosphere simulation can be found at:https://portal.nccs.nasa.gov/datashare/G5NR/DYAMONDv2/GEOS_6km_Atmosphere-MITgcm_4km_Ocean-Coupled/GEOSgcm_output/.
In particular, the dataset contained in the folder geosgcm_surf/ were used in this study.
The ocean-only LLC2160 simulation can be download fromhttps://data.nas.nasa.gov/ecco/data.php?dir=/eccodata/llc_2160/compressed. The variables used in this study are U (east-west velocity component), V (north-south velocity component), oceTAUX (east-west wind stress component), and oceTAUY (north-south wind stress component).
Â
Please, let us know if you have any more concern.
Kind regards,
Hector Torres
JPL, Caltech
Citation: https://doi.org/10.5194/egusphere-2022-294-AC2
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- 1
Hector S. Torres
Patrice Klein
Jinbo Wang
Alexander Wineteer
Bo Qiu
Andrew F. Thompson
Ernesto Rodriguez
Dimitris Menemenlis
Andrea Molod
Christopher N. Hill
Ehud Strobach
Hong Zhang
Mar Flexas
Dragana Perkovic-Martin
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(26835 KB) - Metadata XML